The present invention relates to prosthetic devices for reconstructing the humerus in human beings, and specifically to a modular humeral prosthetic device comprising stem and head mechanisms readily attachable and detachable to and from each other for allowing intra-operative modification of the device. Prior humeral prosthetic implants have been employed having a stem element for implantation within the medullary canal of a human humerus and a head element for engagement within the glenoid cavity of the human scapula. Such devices do not however achieve true anatomic compatibility with the proximal end of a human humerus and do not provide capability for modification of humeral head size during intraoperative surgery other than by replacement of the entire implant. Although modular devices for implantation in the human femur such as applicants' APR brand hip implant system are known, such implant devices cannot achieve anatomic compatibility with the proximal humeral area and are structurally contradistinct with respect to humeral or scapular tissue attachment or engagement, and load, stress and force distribution and tolerability.
The object of the invention therefore is to provide a modular prosthetic device which is anatomically compatible with the proximal human humerus and scapula and provide the most effective distribution of loads, stresses and forces which are peculiar to the proximal humeral area.